


Day One

by FellQueen (Nikasha)



Series: Kinktober 2019 [1]
Category: Undertale (Video Game)
Genre: Blow Jobs, Kinktober 2019, M/M, Masturbation, Mind Control, Riding, Underfell, Underfell Grillby, Underfell Sans, Voyeurism, non-con, sansby - Freeform
Language: English
Status: Completed
Published: 2019-10-02
Updated: 2019-10-02
Packaged: 2020-11-15 01:00:51
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 1
Words: 1,442
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20857616
Author URL: https://archiveofourown.org/users/Nikasha/pseuds/FellQueen
Summary: Day OnePrompt: Mind control / HypnosisPairing: Underfell Sansby





	Day One

**Author's Note:**

> Don’t look at me like that.  
List I’m using is in the end notes. Content warnings are all in the tags. The non-con is clear, but I tried to not make it super in your face.  
Enjoy! And wish me luck, I haven’t done October anything before now.

The forest was usually dark at this time of night, but purple flames cast light on the trees as a monster passed.  
Grillby shifted to glance back over his shoulder, in disbelief of his fortune. Sans was still following him. The little bell on his collar chimed every so often when Sans took a particularly large step, and magic pulsed from it with the sound.  
Grillby was careful as they marched back into town. Anyone that saw would surely report it straight to the Captain and then Grillby would be less than ashes and dust. He would have had Sans shortcut them back, but he didn’t know the effect it would have on the magic keeping him tame...  
It didn’t matter. They reached the bar without incident, the floor already clear from closing for the night an hour ago.  
“Go to the back,” he ordered to Sans in his rasping hiss, watching with satisfaction as the normally obstinate monster just obeyed. He closed the front door and locked it, then added a sensor. Just in case.  
Sans was standing in the middle of the back room when Grillby found him, looking around blankly like he didn’t quite understand what was happening. Grillby walked over and grabbed him by the collar, causing the bell to chime. Sans shuddered.  
The elemental leaned in to get a look at Sans’s face. He noted the hazy eyelights and loose set of his jaw. “Good boy...Ready to play, Sansy?”  
Even that nickname didn’t get a twitch. He tilted his head into Grillby’s warm touch on the side of his skull, humming softly. Cute. “Get on your knees.”  
Sans went, the click of his bones settling against the wooden floor making Grillby note that he would probably ache in the morning. He undid his slacks and tugged his dick free, stroking himself and sighing as Sans looked on blankly. “Make yourself useful,” he said shortly.  
Sans tilted his head the barest measure, apparently confused. The magic took away his free will, but also took away some measure of thought process as well.  
He huffed, irritated. “Suck me.”  
That, at least, Sans could gather. He scooted closer and took the purple fire in hand, licking over his gold metal tooth. Grillby felt a shiver of fear at the sight of his jagged teeth, but didn’t move as the skeleton drew his tongue up the underside of his cock.  
He let out another sigh, shifting his legs apart slightly. He kept his gaze on the normally rebellious skeleton at his feet, taking every order without question. “Touch yourself,” he said, and trailed off into a moan as Sans took him in his mouth.  
Sans paused, then gripped Grillby with one hand as the other trailed down to slide into his shorts, hand working unseen. But Grillby could see his hand moving beneath the fabric.  
It took a moment for Sans to figure the pattern out, but once he did, he started moving his head back and forth over the dick in his mouth, slurping at him as his sockets lidded. His other hand brushed over his pelvis, fingers tracing around the dips and curves with familiarity. He kept his teeth away as he slicked his tongue along the magic in his mouth and hummed.  
The elemental suddenly grabbed Sans’s skull, stopping his motions, as heat surged up his spine and he fought back the tide of pleasure. Sans still licked at him, so he snapped, “Stop.” The instant obedience almost overwhelmed him anyway, just having the bastard listen so well.  
He pulled himself free from Sans, watching the skeleton blink at him and pant, saliva dripping from his teeth and tongue. “Strip.”  
The movements weren’t graceful or seductive, just Sans trying to shuck off his clothes, but Grillby watched with rapt attention, hand moving over himself slowly. Sans stopped when he was bare, looking up expectantly. The bell chimed as he turned.  
Despite touching himself earlier, Sans’s pelvis was devoid of magic. Grillby hummed and knelt, teasing his hands over Sans’s femurs and around his pelvic inlet. Sans shivered and exhaled shakily, but he was surprisingly quiet.  
“Get yourself off,” he ordered roughly, voice crackling.  
Sans leaned back slightly and his blood red magic swirled downwards to begin to form.  
Grillby interrupted him. “Make a cunt.”  
Sans’s magic swirled almost uncertainly, a furrow appearing on his brow, before shaping into what he had demanded. Sans teased his fingers over the opening, legs spreading slightly as Grillby watched, hand moving more quickly over himself.  
He tried to be patient and let Sans move at his own speed, but he seemed hesitant, phalanges moving over his entrance and clit with precision, but not pressing in. “Sans,” he said, tone warning.  
Hazy red eyelights flicked up to meet his gaze. They searched his face. Grillby reached out to grip his collar, tugging him close and making the bell chime as Sans gasped. “Listen to me.”  
Sans nodded, hands coming up to grab Grillby’s wrist. His fingers were wet and hissed against his fire.  
Grillby pressed him to the floor, hand lingering against the collar, before he retreated.  
Sans stayed put for a moment before the last command kicked in, and he reached between his legs, first gently caressing, then finally pushing his fingers inside. He arched, moaning, and Grillby raked his gaze over the expanse of white, scarred ribs expanding and relaxing again.  
The elemental stood, beginning to stroke his dick again as he watched Sans pant and writhe, pushing his fingers into himself slowly, then more and more quickly. Grillby kept pace with his hand, warmth crawling across him and making the purple flames spark and flare. As Sans trailed his other hand down to drag his sharp fingertips across his hip, Grillby smoothed his thumb over his slit, panting.  
Sans started to moan more loudly, heels digging into the floor as he pushed his fingers deep into his opening. Grillby grit his teeth. “Say my name.”  
“Gr...Grillbz,” Sans gasped out, shuddering.  
“No. My name,” he hissed.  
Sans locked eyes on him, tongue drawing over the gold tooth. “Grillby,” he rasped out into the air. He must have hit something, because he suddenly groaned, hips jerking. “F-Fuck...”  
“Stop.” Grillby forced his own hand to still even as he said it.  
Sans groaned again, this time in protest, but withdrew his fingers. He stared up at Grillby, waiting.  
His cock throbbed. Grillby pulled over a chair and sat, smacking his thigh. “Come here.”  
Sans slowly pushed to his feet, staggering a bit as red began to trail down his leg. He wandered over to Grillby and stood between his legs, unprotesting as the elemental groped his tailbone. He just hissed, eyes closing.  
Grillby smirked, flames snapping with satisfaction. “Ride my dick.”  
Sans clambered on, getting a grip on his shoulders and straddling his lap with his entrance just over Grillby’s cock as he balanced himself.  
The fire monster didn’t wait. He gripped himself in one hand and used the other to pull Sans down, spreading him open. Their cries were loud in the room, Sans in surprise, Grillby’s in ecstasy.  
Sans didn’t take long to recover. He resettled his weight on his knees, then started moving, hips working slowly, then quicker and smoother as he found his rhythm. The bell rattled each time he jerked, a quick little noise.  
Grillby groaned. He wouldn’t last, he knew, not after this long. He reached down to rub his fingers against Sans’s clit, warm fire keeping things hot.  
The skeleton thrust into the touch, whining softly as he moved and clenched down on the heat inside of him. “Grillby!”  
And then his breath hitched and he was cumming, pulsing around Grillby as magic coated them both. The elemental grabbed him by the spine and hip and began thrusting up into him with sharp grunts, chasing the feeling crawling up to overwhelm him. He jerked and pulled Sans tight to his lap, hot threads of magic pulsing into Sans and making the skeleton moan along with him.  
It took a moment for him to come down. His own thoughts were hazy at this point, laced with contentment. He felt something hook onto his suit jacket and pull him forward sharply, his eyes shooting open.  
Sans grinned at him, all teeth and sharp edges. His eyelights were bright. “Heh. Hope you enjoyed yourself there, _pal._ Because I’m about to have myself a fucking _g o o d t i m e.”_  
A blaster whirred nearby and Grillby’s afterglow faded fast. If he survived this, he was going to kill Muffet for giving him this stupid toy.

**Author's Note:**

> Thanks for reading!  
Using this list, switching some out if I don’t like the prompt:  
https://twitter.com/idek_uggy/status/1178349575725174786?s=21
> 
> Day 2 is somnophilia!


End file.
